Scrapyard Dog in 7:46.84 by Noxxa

Game objectives

• Emulator used: BizHawk 1.11.8.2
• Aims for fastest time
• Takes damage to save time
• Uses warps
• Manipulates luck (minor)

About the game

Tricks

• Gameplay is 30fps. Input is only accepted every other frame. However, the game is 60fps during score countdown at the end of each level.
• There are four warps in this game, two of which are taken. Junkyard 2 to Forest 1 (world 1>3), and Forest 1 to Ice 1 (world 3>6). Other warps that exist are Junkyard 4 to Mountain 1 (world 1>4) and City 1 to Desert 1 (world 2>5), but those are not entered. For reference, the seven worlds are: Junkyard, City, Forest, Mountain, Desert, Ice, Castle.
• Horizontal movement starts at 1px/frame for a few frames, before accelerating up to 2px/frame. Jumping in the air speeds up the acceleration.
• Jumping costs 1 pixel on landing. Therefore, it is important to minimize the number of jumps throughout the stages.
• There are limited jumping heights. Depending on the initial acceleration, there are three possible jumping heights when making a jump, and four in total. Because of this, sometimes it seems like I am overshooting a jump when in reality this is due to the restrictions on jumping.
• Only one projectile can be on screen at a time. With cans, throwing a new one will remove the old one; with the gun, you cannot fire until the bullet has hit an enemy or is off screen.
• Invincibility glitch: having an attack hitbox (can or bullet) inside an enemy will make it not do collision checks with the player for as long as the can/bullet touches it. This is useful for passing through several enemies, sometimes even bosses, unharmed.
• Acceleration carryover: Acceleration carries over between stages. If you end with zero acceleration in a stage, then you have to accelerate at the start of the next stage; if you don't, then you can immediately start moving forward.

Stage-by-stage comments

Junkyard 1

• Collecting the letter at the end saves a few frames compared to reaching the right edge of the screen.

Junkyard 2

• I enter a pile of tires to play a can minigame, where I have to select a specific can after they have been shuffled around. I luck manipulate this to be the left-most can to save frames from moving the pointer. The reward of this minigame is a small upgrade. When Louie is small, he cannot fire projectiles, but he can take an extra hit, and he can enter certain small doors. These small doors are used for warps.
• Being small and unable to fire projectiles also makes me unable to perform the invincibility glitch, so some creative dodging is required in a few places.
• The warp door is summoned by crouching on the toilet facing left, next to the office, for roughly a second.

Forest 1

• I enter the shop and leave it immediately. This is done in order to despawn the enemies on the screen. Otherwise, there would be a snake enemy in front of the warp door, which would hit Louie and render him unable to enter it.
• The warp door is summoned by crouching on the tree stump facing left, next to the shop, for roughly a second.

Ice 1

• I discard the small upgrade basically as soon as it saves any time, as I have no need for it any more and the projectiles are too good to keep missing out on.
• Yes, the game uses Ride of the Valkyries for its invincibility theme. Invincibility can be triggered in a few hidden places; there is one here and one in Castle 1 in this run.
• The Ice stage introduces ice floors, where Louie keeps sliding on them until the end or until he jumps off. While sliding, he moves at 3px/f, so it is beneficial to slide on these floors as much as possible. However, jumping off them resets horizontal acceleration, so it also slows down a bit. Generally the speed bonus is worthwhile though.

Ice 2

• I grab the letter at the end to save a few frames compared to sliding all the way through.

Ice 3

• With these moving iceberg platforms, key to optimization is walking along them when they move to the right, and spending as little time on them when they move to the left. However, in one case it was unavoidable to have to walk as it moved to the left, as the minimum jump height would make me overshoot and holding back would end up being even slower in the end.
• There is one iceberg with an ice floor on the right side. Because ice floors reset horizontal acceleration, it isn't possible to get the maximum jumping height off of it. Because of this I have to wait for some time until the next platform is close enough, even though it otherwise looks like I could reach it much faster.

Ice 4

• This stage precedes a bossfight, so it has a chest with a gun with infinite ammo at the end. Guns are otherwise available in shops, but they have limited ammo then.

Ice 5

• This snowman bossfight is one of the most annoying bossfights in the game. It has 15 HP, and walks back and forth firing icicle projectiles from its head at a diagonal angle down. Its only weak spot is its 'heart' on its center front. The rest of it is invincible. Also, half of the floor is ice.
• The ice is actually beneficial in a way, as it allows me to slide through him unharmed with the right (really precise) invincibility glitch setup.
• Because its weak spot is in its front, to be able to hit it from behind I need to be very close to him. It was tricky to keep staying right behind him, using bullets and the invincibility glitch to not die, staying left enough to hit the weak point but not far enough to pass it, while the ice would screw up my ground movement.
• Because of acceleration carryover, I can't really do an elaborate victory dance here, and have to settle with walking right in order to set up acceleration for the next stage.

Castle 1

• This stage has a lot of enemies to dodge.
• The Ride of the Valkyries invincibility item makes a return near the end of the stage here.

Castle 2

• This is a maze sort of stage. It has several doors that lead to a few different places, and it easily becomes a confusing mess. However, knowing what doors are needed to reach the exit, this stage is cleared very quickly.
• We get another infinite gun at the end of this stage. This one will carry over all the way to the end of the game.

Castle 3

• This stage features a boss rush. All of the previous six worlds' bosses are fought here. However, because of all the warps, five of them we have never met before.
• Every boss room has two or three doors at the end. They can only be accessed once the boss' hitpoints reach zero. One door leads to the next bossfight, one door leads back to the same bossfight, and if there is a third door, it leads to a shop or minigame. I always go for the door of the next bossfight, because the others just waste time.
• Most boss strategies come down to finding ways to rapid-fire them to death quickly, remembering that only one bullet can be on screen at a time.
• The Junkyard boss is a rat in a tank. It has 5 hitpoints, and the tank itself is invincible. I jump over him so I can rapid-fire him in be back on the way down, and kill him near-instantly that way.
• The City boss is a wolf in an UFO. It has 10 hitpoints. With a specific rate of fire, I can use the invincibility glitch to walk through him while damaging him, then jump over him to avoid him when the bullets would pass him on the right. Even when the boss' hitpoints are down, it could still kill me by collision damage while I try to enter the door - so, I fire a shot to the left, triggering the invincibility glitch for long enough that I could enter the door unharmed.
• The Forest boss is a toad. It has 10 hitpoints. I rapid-fire into it, then jump over it landing right where the door is.
• The Desert boss is a ghostly bandit (oddly, in the boss rush it appears before the Mountain boss, out of order). It has 10 hitpoints. It has a habit of turning intangible and moving around erratically. I get into position to load bullets into it as soon as it reappears, which gives me just enough time to kill it in one phase. The positioning for this actually has to be pixel perfect.
• The Mountain boss is a raccoon with a jetpack and a missile launcher. It has 10 hitpoints. With a specific jumping and shooting pattern, I can kill it in one jump.
• The Ice boss is an abominable snowman. We've seen this one before, but this time there are no ice floors, which also means I can't pass through him this time. So I have to pass over him instead, which requires a very precise jump with application of the invincibility glitch. Then he is shot in the back as usual.
• The chest in the end gives a shield item, which allows Louie to take an extra hit before dying. This will be used for the final boss fight.
• The level timer gives 800 seconds for this level. I used 34. The remaining 766 seconds take a while to count down.

Castle 4

• After some last brief castle action, Louie finally meets Mr. Big himself. He has 15 hitpoints. Thanks to the shield item, I can just get up close and rapid-fire gun Mr. Big to death, not worrying about him hitting me. This turned out to be the best application of the shield item in this stage.
• With Mr. Big shot to bits and Louie's dog Scraps saved, time to commemorate all the worlds we mostly haven't visited!

Final notes